Chelants are used in a variety of applications including food processing, soaps, detergents, cleaning products, personal care products, pharmaceuticals, pulp and paper processing, water treatment, metalworking and metal plating solutions, textile processing solutions, fertilizers, animal feeds, herbicides, rubber and polymer chemistry, photofinishing, and oil field chemistry. Commercially available chelants are typically aqueous solutions having a chelant activity of about 40 percent to about 60 percent by weight.
Aminocarboxylic acid chelants and their salts (aminocarboxylates) may be prepared by a number of known techniques. On an industrial scale, a typical process involves the reaction of an amine with formaldehyde and cyanide in the presence of an alkaline metal hydroxide (see e.g., Bersworth, U.S. Pat. No. 2,407,645, which is incorporated herein by reference).
There are various disadvantages associated with the known manufacturing processes. One such disadvantage is that chelants produced by methods that utilize an alkaline metal hydroxide as a reagent, including the Bersworth process described above, in general are hygroscopic and become caked when exposed to the atmosphere. Chelants with better atmospheric stability and solid flowability are desirable in the industry.